639664111 has 2 divisors, whose sum is σ = 639664112. Its totient is φ = 639664110.

The previous prime is 639664057. The next prime is 639664121. The reversal of 639664111 is 111466936.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639664111 - 2⁹ = 639663599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639664121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319832055 + 319832056.

It is an arithmetic number, because the mean of its divisors is an integer number (319832056).

Almost surely, 2^639664111 is an apocalyptic number.

639664111 is a deficient number, since it is larger than the sum of its proper divisors (1).

639664111 is an equidigital number, since it uses as much as digits as its factorization.

639664111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 37.

The square root of 639664111 is about 25291.5818208352. The cubic root of 639664111 is about 861.6230890237.

It can be divided in two parts, 6396 and 64111, that added together give a palindrome (70507).

The spelling of 639664111 in words is "six hundred thirty-nine million, six hundred sixty-four thousand, one hundred eleven".